代码

#include <iostream>
#include <cstring>

using namespace std;

class My_string
{
private:
    char* cstr;
    int len;
public:
    My_string():cstr(NULL),len(0)                     //无参构造
    {
    }

    My_string(const char* str)      //有参构造
    {
        this->len = strlen(str);
        this->cstr = new char[(this->len)+1];
        strcpy(this->cstr,str);
    }

    My_string(const My_string &other)//拷贝构造函数
    {
        this->len = other.len;
        this->cstr = new char;
        strcpy(this->cstr,other.cstr);
    }

    ~My_string()                     //析构函数
    {
        delete this->cstr;
    }

    bool empty()                     //判断是否为空
    {
        return this->len == 0 ? true : false;
    }

    int size()                       //返回字符串的长度
    {
        return this->len;
    }

    char &at(int index)              //定位函数
    {
        return *(this->cstr+index);
    }

    char* c_str()                     //转化为C风格的字符串
    {
        return this->cstr;
    }

};

int main()
{
    My_string s1 = "hello";
	//e 0 5 hello
    cout << s1.at(1) << " " << s1.empty() << " " << s1.size() << " " << s1.c_str() << endl;

    My_string s2(s1);
	//hello
    cout << s2.c_str() << endl;

    My_string s3;
	//1
    cout << s3.empty() <<endl;

    My_string* s4 = new My_string(s1);
	//hello 0
    cout << s4->c_str() << " " << s4->empty() << endl;

    delete s4;
    //e 0 5 hello
    cout << s1.at(1) << " " << s1.empty() << " " << s1.size() << " " << s1.c_str() << endl;

    return 0;
}

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